Post-Election Audit
There are 3 types of post-election audits which can be performed following an election. They include Fixed Rate, Tiered, and Risk-Limiting audit models. A board of elections should choose one of the three methods to perform a post-election audit.
Fixed Rate Audit
In this model, jurisdictions are required to randomly select a fixed or flat percentage of precincts or machines to audit. All voter verifiable paper records for the selected precincts or machines are hand-counted and compared to the electronic tallies. If the initial percentage counted is shown to have a discrepancy, an additional percentage of precincts or machines is added to the audit.
Tiered Audit
In this model, jurisdictions are required to randomly select precincts or machines to audit using a sliding percentage based on the margin of victory. The smaller the margin of victory, the more units are required to be audited; the larger the margin of victory, the fewer units are required to be audited. All voter verifiable paper records for the selected precincts or machines are hand-counted and compared to the electronic tallies. If the initial percentage counted is shown to have a discrepancy, an additional percentage of precincts or machines are added to the audit.
Risk-Limiting Audit
In this model, jurisdictions are required to randomly select a number of precincts or machines to audit based on a large, predetermined confidence rate and chance of catching and correcting incorrect electoral outcomes. All voter verifiable paper records for the selected precincts or machines are hand-counted and compared to the electronic tallies. This method has a known pre-specified minimum chance of requiring a full hand count to show a different outcome in the race to be audited.
Preparing for the Audit